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. 1992 Nov;132(3):783–787. doi: 10.1093/genetics/132.3.783

Direct Measurement of in Vivo Flux Differences between Electrophoretic Variants of G6pd from Drosophila Melanogaster

J Labate 1, W F Eanes 1
PMCID: PMC1205214  PMID: 1468630

Abstract

Demonstrating that naturally occurring enzyme polymorphisms significantly impact metabolic pathway flux is a fundamental step in examining the possible adaptive significance of such polymorphisms. In earlier studies of the glucose-6-phosphate dehydrogenase (G6PD) polymorphism in Drosophila melanogaster, we used two different methods, exploiting both genotype-dependent interactions with the 6Pgd locus, and conventional steady-stake kinetics to examine activity differences between the two common allozymes. In this report we use 1-(14)C- and 6-(14)C-labeled glucose to estimate directly genotype-dependent flux differences through the pentose shunt. Our results show the G6pd(A) genotype possesses statistically lower pentose shunt flux than G6pd(B) at 25°. We estimate this to be about a 32% reduction, which is consistent with the two former studies. These results reflect a significant responsiveness of pentose shunt flux to activity variation at the G6PD-catalyzed step, and predict that the G6PD allozymes generate a polymorphism for pentose shunt flux.

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Selected References

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